The present invention relates to an electrophotographic process and more particularly a method for controlling the image formation in an electrophotographic process so that all the copies from the first to the last copy may have the uniform density and density difference in image.
It is well known in the art of electrophotography that when a photosensitive member is exposed to light prior to the primary charging (this step will be referred to as "pre-exposure" in this specification), the surface potential charged by the primary charging is decreased as compared with that of a photosensitive member which is not subjected to the pre-exposure, so that the density of the image is decreased.
The surface potential which the photosensitive member may maintain is decreased as the number of cyclic operations is increased so that the density of the image developed is accordingly decreased. Therefore, when the photosensitive member is used repetitively for reproducing a number of copies from the same original, there is a difference in density between the first copy and the subsequent copies. That is, it is impossible to reproduce copies having the same density and density difference.